"Tests were done with less than .01 ppm of ozone reveal that "the levels of oxygen in the blood increase relatively quickly and remain at a high level for the duration of the experiment." They conclude by stating that "atmospheric ozone has a positive effect on animals and people. It is important to note its positive effect on the breathing system, blood composition, arterial pressure, immune system, general feeling of well-being, and mental and physical work capability." They note further that "the ozone-ion complex is a necessary component of fresh air that gives it a curative effect." If that isn't enough, we find that in the journal Priroda (1976, No. 9, p.26), the above researchers report that, with tests of 0.005 to 0.02 ppm of ozone for 2-5 months, "an increase in the resistance to the cold, to the presence of toxic substances , and to anemia was discovered." In addition, they discovered an increase in hemoglobin and quantity of red blood corpuscles as well. The same article refers to the decrease in complaints of stuffiness (3.8 times less complaints) and 44% more positive remarks for an average of 0.0075 ppm (less than 0.01 ppm) of ozone".